In the United States, there is typically an adequate supply of fresh drinking water available in most regions of the country. Even in areas where water supplies are scarce, efforts have been made to transport water from where it is available, to where it is needed. For example, a significant amount of water is currently being transported from the Colorado River, via the California Aqueduct, to heavily populated, but dry, regions of Southern California, so that sufficient water will be available, not only for drinking purposes, but for agriculture and irrigation. Other means of supplying and transporting water, such as through a network of utilities, and pipelines, including those from lakes, reservoirs, rivers, glaciers, etc., are also in existence.
Nevertheless, there are many geographical areas throughout the country and world where fresh drinking water is not readily available, or where it might be inconvenient or cost prohibitive to transport the water to where it is needed. These areas include mountainous regions, rural areas, islands, etc. There are also large population centers near the coastline, such as in dry or arid climates, where there is sufficient seawater, but not enough drinking water available to support the population.
Accordingly, desalination systems and methods to produce fresh drinking water from seawater have been developed in the past. The key to any desalination system is the ability to separate the contaminants, including salt and other impurities, from the base water, which in turn, can produce fresh drinking water. For purposes of simplicity, the term “seawater” will be used herein to refer to any contaminated water that needs to be purified, whether it is actually water from the sea, or water from any other source.
At least three different types of desalination systems are currently in use today, to varying degrees of success, including 1) the thermal method, which uses heat or other means to convert seawater into water vapor, such as by boiling, 2) the membrane method, which uses a relatively thin permeable layer of material to separate the water from the salt, and 3) the freeze crystallization process, which takes advantage of the freezing process and the phase diagram of seawater to produce fresh drinking water.
The present invention is utilized in conjunction with a variation of the freeze crystallization process. The freeze crystallization process is different from other processes in that seawater is subjected to cooling temperatures, such as via a refrigerant, which causes the seawater to freeze, wherein the freezing is used to help form solid ice crystals made from pure water, which can then be separated from the salt contaminants contained in the residual base water.
Because of the drawbacks of existing desalination methods and systems, however, there is a need for a highly efficient and cost effective desalination system that allows fresh drinking water to be produced from seawater on a continuous basis.